Malaria is a mosquito-borne infectious disease caused by the bite of female Anopheles mosquitoes, which spread infectious Plasmodium parasites into a host. Traditional malaria symptoms include fever, chills, headache, muscle aches and fatigue. Nausea, vomiting and diarrhea also are common. Untreated malaria can lead to severe disease, kidney failure and death. Neurological complications can occur in severe cases, most commonly in young children.

Most malaria cases occur during rainy periods in endemic regions. The World Health Organization estimates that in 2020, globally about 240 million people had malaria and about 627,000 of them died. A disproportionate burden of malarial disease occurs in Sub-Saharan Africa, where children under age 5 account for about 80% of all malaria deaths.

A vaccine to prevent malaria is available; however, its variable efficacy underscores the need for new interventions that offer high-level protection against disease. Malaria is a research priority at NIAID, which is the lead U.S. government agency investigating the disease. Scientists are researching improved vaccines and preventive interventions as well as mosquito control techniques, easy-to-use diagnostics, and improved therapies as parasites continue to develop resistance to currently available antimalarials.

Escherichia coli (E. coli) bacteria live in the intestines of people and animals, and are key to a healthy intestinal tract. Most E. coli strains are harmless, but some can cause diarrhea through contact with contaminated food or water while other strains can cause urinary tract infections, respiratory illness and pneumonia.

Why Is the Study of E. coli a Priority for NIAID?

CDC estimates that 265,000 Shiga Toxin-Producing E. coli (STEC) infections occur each year in the United States. Approximately 36 percent of these infections are caused by E. coli O157:H7.

How Is NIAID Addressing This Critical Topic?

Scientists in NIAID labs and NIAID-supported scientists are using basic, clinical, and applied research to better understand how to detect, treat, and prevent foodborne diseases.

Coronaviruses are a large family of viruses that usually cause mild to moderate upper-respiratory tract illnesses in humans. However, three coronaviruses have caused more serious and fatal disease in people: SARS coronavirus (SARS-CoV), which emerged in November 2002 and causes severe acute respiratory syndrome (SARS); MERS coronavirus (MERS-CoV), which emerged in 2012 and causes Middle East respiratory syndrome (MERS); and SARS-CoV-2, which emerged in 2019 and causes coronavirus disease 2019 (COVID-19).

Building on previous research on SARS and MERS, NIAID scientists and NIAID-supported researchers mobilized quickly to develop COVID-19 therapeutics, vaccines and diagnostics. Researchers continue to conduct basic research to understand how coronaviruses infect cells and causes disease, and what interventions can detect, prevent and stop the spread of disease.

Syphilis is a common sexually transmitted infection (STI) caused by Treponema pallidum bacteria. If untreated, syphilis can result in adult neurological and organ damage as well as congenital abnormalities, stillbirth, and neonatal death. After decades of relatively low prevalence, syphilis cases have risen sharply since 2000. NIAID participates in the National Syphilis and Congenital Syphilis Syndemic Federal Task Force and supports a broad syphilis research portfolio with a goal of advancing syphilis diagnosis, prevention and treatment. 

Sexually transmitted infections (STIs) are caused by pathogens transmitted from person to person through sexual contact. STIs can be caused by bacteria, viruses, or parasites. STIs have a devastating impact on adults and infants and affect millions of people in the United States annually. Infection with certain STIs can increase a person’s risk of developing cancer and can increase the likelihood of acquiring or transmitting HIV. In addition, STIs can cause long-term health complications, especially in the reproductive and central nervous systems. In rare cases, STIs can lead to serious illness or death. Research is urgently needed to help reduce the public health burden of STIs.

Respiratory syncytial virus (RSV) infects the lungs and breathing passages, and, in the United States, nearly all children have been infected with RSV by age two. In healthy people, symptoms of RSV infection are usually mild and resolve within a week. However, RSV can cause serious illness or death in vulnerable individuals, including premature and very young infants, children with chronic lung disease or congenital heart disease, and people who are over age 65. In the U.S., RSV is the most common cause of bronchiolitis (inflammation of the small airways in the lungs) in children younger than one year old and causes approximately 58,000 hospitalizations among children under five annually. RSV infection is estimated to cause about 14,000 annual deaths in U.S. adults over age 65. Globally, RSV affects an estimated 64 million people and causes 160,000 deaths each year.

NIAID conducts and supports basic research on RSV to improve understanding of the virus and how it causes disease, as well as factors in animals and humans that affect susceptibility to RSV infection. Research is also underway to develop vaccines to prevent RSV.

Prion diseases are transmissible, untreatable, and fatal brain diseases of mammals. Their cause is highly unusual: The host’s normal prion protein can, for unknown reasons, malfunction and assemble into structured aggregates called prions that cause infectious brain disease. This process – which can be underway for years before symptoms appear – likely causes the most common form of prion disease in people, sporadic Creutzfeldt-Jakob disease (CJD). Other forms of human prion diseases include variant CJD, fatal familial insomnia, Gerstmann-Straussler-Scheinker Syndrome and Kuru.

In livestock and wildlife, prion diseases such as scrapie (sheep), chronic wasting disease (deer, elk, moose), and mad cow disease (cattle) can spread by casual contact or contamination of feeds or the environment. Prions also can be infectious if inadvertently transferred from person to person by invasive medical procedures.

Prion disease symptoms reflect the brain being destroyed and can range from memory loss and unstable movement to being unable to sleep or realize the need to eat.

NIAID scientists have focused research on prion structures, biochemistry, cell biology, pathogenesis, diagnostics, and therapeutics. NIAID also is exploring similarities between prion diseases and other protein misfolding diseases, such as Alzheimer’s and Parkinson’s diseases, Lewy body dementia, and chronic traumatic encephalopathy.

Plague, caused by the bacterium Yersinia pestis, is a disease that affects humans and other mammals. People typically get infected after being bitten by a rodent flea that is carrying the bacterium or by handling a plague-infected animal. Although the disease killed millions in Europe during the Middle Ages, antibiotics effectively treat plague today. Without prompt treatment, plague can cause serious illness or death. Human plague infections continue to occur in the western United States, but significantly more cases occur in parts of Africa and Asia.

Why Is the Study of Plague a Priority for NIAID?

Plague is a category A pathogen which are those organisms/biological agents that pose the highest risk to national security and public health because they can be easily disseminated or transmitted from person to person, result in high mortality rates and have the potential for major public health impact, might cause public panic and social disruption, and require special action for public health preparedness.

How Is NIAID Addressing This Critical Topic?

NIAID conducts and supports research on the diagnosis, prevention, and treatment of infections caused by microbes, including those that have the potential for use as biological weapons. The research program to address biodefense includes both short- and long-term studies targeted at designing, developing, evaluating, and approving specific tools (diagnostics, drugs, and vaccines) needed to defend against possible bioterrorist-caused disease outbreaks.

Gonorrhea is a sexually transmitted infection (STI) caused by the bacteria Neisseria gonorrhoeae. N. gonorrhoeae infects the reproductive tract, including the cervix, uterus, and fallopian tubes in women, and the urethra in women and men. N. gonorrhoeae can also establish infection in the mouth, throat, eyes, and rectum. It is becoming more difficult to treat gonorrhea, as strains have been isolated that are resistant to the last antibiotic approved for treatment. NIAID supports a comprehensive, multidisciplinary program of research on N. gonorrhoeae that includes basic research on pathogens, improved diagnostics, preventive vaccines, and additional alternative treatments. 

Schistosomiasis, also known as bilharzia or snail fever, is an acute and chronic disease caused by parasitic flatworms called schistosomes or blood flukes. Most human infections are caused by Schistosoma mansoni, S. haematobium, or S. japonicum. The parasites spend part of their lifecycle in freshwater snails. The infectious, larval form emerges from the snail and contaminates water.

People who contact contaminated water during recreational, agricultural, or domestic activities become infected when the fork-shaped larval worms penetrate their skin, travel to blood vessels, and develop into adults. The release of eggs from female worms triggers symptoms in infected people, which can include abdominal pain, diarrhea, and blood in the urine. In children, repeated infections may cause anemia and stunted growth. Chronic infections frequently result in serious damage to the liver, intestines, and bladder. Women who are exposed to infested water through such routine tasks as clothes washing can develop urogenital schistosomiasis, which may result in tissue damage that increases the risk of HIV transmission.

Why Is the Study of Schistosomiasis (Bilharzia) a Priority for NIAID?

Although the parasites that cause human schistosomiasis are not found in the United States, at least 220 million people are infected worldwide, particularly in rural communities where people routinely collect water from lakes, rivers or small bodies of water for household or agricultural use. Among parasitic diseases, schistosomiasis is second only to malaria in terms of the high disease and economic burden it imposes

How Is NIAID Addressing This Critical Topic?

NIAID-supported investigators study many aspects of schistosomiasis to find new ways to prevent and treat the disease. Research is directed at the various life-stages of parasite itself as well as the freshwater snails that serve as an intermediate host.

Like other so-called neglected tropical diseases (NTDs), schistosomiasis generally impacts the world’s poorest people. Learn about NIAID research efforts on other NTDs.

The NIAID-funded Schistosomiasis Research Center provides investigators with a number of resources to advance their studies, including egg and larval parasites, snails and molecular reagents and other tools needed to conduct research.

This video describes the resources available from the Schistosomiasis Research Center.

VIDEO: Scientists studying schistosomiasis rely on NIAID for an unusual research resource—snails.